Acrylic acid derivatives of perfluoroalkyl group-containing alcohols, for example, CF3(CF2)7CH2CH2OCOCH═CH2, are used in large quantity as synthetic monomers of fluorine-containing copolymers constituting water- and oil-repellents for textile. Perfluoroalkyl alcohols serving as acrylated precursors of the acrylic acid derivatives are widely used as, for example, surfactants.
[Patent Document 1] JP-B-63-22237
In Patent Document 2, it is described that in a surface-treating agent of a substrate, the expression of water- and oil-repellent properties of (meth)acrylate containing a perfluoroalkyl group (Rf) depends on the orientation of the Rf group on a treated film and further described that for the orientation of a Rf group, the presence of melting point in a microcrystal originating the Rf group (having 8 or more carbon atoms) is required, and, therefore, perfluoroalkyl group-containing (meth)acrylate including a perfluoroalkyl group having 8 or more carbon atoms has been used. In addition, it has been shown that in the case of not containing an isocyanate monomer, the contribution to water- and oil-repellent properties, which is observed in the (meth)acrylate including a perfluoroalkyl group having 8 or more carbon atoms, is insufficient when the perfluoroalkyl group-containing (meth)acrylate includes a perfluoroalkyl group having 8 or less carbon atoms.
[Patent Document 2] WO 2004/035708
On the other hand, in recent years, perfluorooctanoic acid (PFOA) or perfluoroalkyl group-containing carboxylic acid (PFCA) including a perfluoroalkyl group having 8 or more carbon atoms, which do not occur in nature, have been observed to be present in the air, rivers, and so on. It has been reported that, among these compounds, those having perfluoroalkyl groups including about 8 carbon atoms have high bioaccumulation potential and therefore have an environmental problem. Therefore, it is anticipated that the manufacturing and the use of these compounds will become difficult in the future.
Note that, presently, it is suggested that a possibility that among telomer compounds used as raw materials of surface-modifying agents such as water- and oil-repellents, compounds including perfluoroalkyl groups having 8 or more carbon atoms are converted into PFCA in the environment. Therefore, it is anticipated that the manufacturing and the use of these compounds will be restricted. On the other hand, though compounds including perfluoroalkyl groups having 6 or less carbon atoms are recognized to be low in bioaccumulation potential, the compounds including perfluoroalkyl groups having 6 or less carbon atoms are difficult to achieve performance required in products such as surface-modifying agents.